Allow only one instance - but exit the first

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Hi,

I want to allow only one instance of my application. So using Mutex seems to be a good possibility to achieve that. But all examples I found describe how to close the instance that was started secondary.

Is there a way to signal the first instance if a second instance starts using (System.Threading.)Mutex? Or is there another clean way to close the first instance of my application if a second instance starts?

Thanks!! :)

Gobble-G

Posted 11-Aug-10 7:20am

Gobble-G

Updated 11-Aug-10 7:45am

v2

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Solution 2

Yeah, this works great.

The only thing I had to add is a thread synchronization to close the application. As I use WPF I replaced your line:

this.Close();

by:

this.Dispatcher.Invoke(new Action(() => { Application.Current.Shutdown(); }));

Thank you very much! :)

Posted 11-Aug-10 22:09pm

Gobble-G

Comments

Toli Cuturicu 12-Aug-10 8:41am

Reason for my vote of 1
fake answer

DaveyM69 17-Aug-10 6:53am

Reason for my vote of 4
Although the OP didin't specify or tag as WPF he has added a solution for that situation so counts as an answer as far as I'm concerned.

Gobble-G 17-Aug-10 14:55pm

I'm sorry - I'm new to codeproject.com and not familiar with the manners. What's the problem with my answer? In my opinion my problem was not a specific WPF problem but rather a .NET problem. So why I had to tag as WPF? I'm also using SQL, several WSDL proxies, XML and a few third party libraries. Should I also tag these keywords? %-/

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Jimmanuel · Accepted Answer · 2010-08-11T08:16:00

Instead of a Mutex you could use a ManualResetEvent and have the first instance register a thread pool wait on it. When another instance starts it can attempt to open up the MRE, if it exists then it can set it which will signal the first instance to close and then reset it and then register it's thread pool wait on it.

Something like this:

C#

// all of this happens on startup obviously
bool createdNew = false;
EventWaitHandle instanceEvent = new EventWaitHandle(false, EventResetMode.ManualReset, "MyInstanceEvent", out createdNew);
if (!createdNew)
{
    instanceEvent.Set();
}

instanceEvent.Reset();
ThreadPool.RegisterWaitForSingleObject(instanceEvent, (state, timedOut) =>
{
    instanceEvent.Close();

    // where this is the Form class
    this.Close(); 
}, null, Timeout.Infinite, true);